Aquarium filters of this type are known see for example German Disclosure Document DE-OS 2 301 430. The filter bodies of this known aquarium filter consist of three perforated filter tubes which are positioned with spacing from each other, in which the ring spaces located between the filter tubes form the two filter chambers to receive filter materials. The clear-water chamber is positioned between the inner filter tube and the supply tube which is carried through the inner filter tube for a mammoth pump arranged below the filter body. The aquarium water sucked over the airlift pump and the clear-water chamber thus flows sequentially through the outer and the inner filter chamber. This known construction as a multi-chamber filter has, primarily, the advantage that different filter materials which have different objects can be received in the two filter chambers. For example, a matting of filter material in the outer filter chamber serves to mechanically clean the aquarium water, whereas filter materials such as activated coal, gravel, peat fibers, lava chips, and the like, in the inner filter chamber should serve for chemical treatment or regeneration, respectively, of the aquarium water.
In the known construction, due to the different cross section of the two concentric filter chambers, a strongly increasing flow speed, in radial direction, of the aquarium water will necessarily result. This means on the other hand that the filter material of the inner filter chamber, due to the higher flow speed, will form deposits thereon comparatively quickly and must be frequently cleaned. The cleaning which is necessary with decreasing filtration effect causes some difficulties due to the complicated and interfitting construction of the filter body.